This invention relates to a gripping device for attachment to an elongate flexible member such as a safety rope.
Protective safety rope systems for machinery use ropes which are linked in tension to switch mechanism whereby a significant change in tensioning of a rope causes the associated switch mechanism to operate to cut off power supply to the machinery.
The rope is linked to the switch mechanism via a gripping device which holds the rope and has a hook which engages an eye of the switch mechanism. Known gripping devices have jaws between which a length of the rope is clamped. However, with such known devices it has been found difficult to prevent the rope slipping and losing tension.
This is particularly the case with ropes constructed with a central core and an outer sleeve since the sleeve can pull away from the core under tension.
An object of the present invention is to provide a convenient to use gripping device with which an elongate flexible member such as a rope can be held with improved security so as to prevent or at least appreciably reduce risk of slipping under tension.
According to the invention therefore there is provided a gripping device for gripping an elongate flexible member, said device comprising a housing with a passageway to receive the member running between main inlet and outlet locations, and a clamp mechanism operable to apply a transverse clamping force to the member at a clamping location of said passageway, the passageway having sections running in opposed directions.
With this arrangement gripping of the member can be achieved in a convenient manner simply by inserting the member through the passageway from the inlet to the outlet locations and then operating the clamp mechanism to clamp the member, and this can result in particularly secure gripping of the member in so far as it passes in a first direction and then loops back on itself to pass in a second, opposed direction through the, or a second said passageway section. Preferably there are two passageway sections although if desired there may be three or more sections whereby the elongate member can be passed through the sections to run in successive opposed directions.
The passageway sections may be wholly separate whereby the elongate member extends beyond the housing between such sections through auxiliary inlet and outlet locations. Thus the sections may be defined by through bores each extending wholly through the housing. Alternatively, if desired, the sections may be linked within the housing.
The sections may be of any form and may be arranged in any disposition relative to each other. In one embodiment the sections are straight and may run parallel to each other whereby the elongate member loops back through 180E between successive said sections.
The main inlet and outlet locations may comprise openings in the housing. If desired one or both such locations may additionally incorporate a guide structure to guide passage of the elongate member into or out of the respective passageway section. Conveniently one such guide structure may be provided comprising a frame projecting from the housing and having an opening to receive the elongate member spaced from the housing. Where the passageway sections are wholly separate and auxiliary inlet and outlet locations are provided as aforesaid these may also comprise openings.
The housing may be of any suitable form. In one embodiment the housing comprises a side wall structure bounding an internal cavity closed by opposite end walls.
One or both end walls may be provided with the aforesaid openings defining the main inlet and outlet locations, and the auxiliary such locations where provided, and the cavity may link the openings to define the passageway sections.
The side wall structure may be cylindrical whereby the end walls may be circular. One such end wall may be integral whereby the opposite end wall may be removably attached to the side wall structure e.g. by screws or the like.
The clamp mechanism may be located within the housing e.g. within the aforesaid cavity and may comprise a clamp member having at least one abutment surface movable relative to a respective fixed surface of the housing in at least one said passageway section thereby to trap the elongate member between such surfaces.
In one embodiment the member has a plurality of abutment surfaces movable relative to a plurality of said fixed abutment surfaces in the respective passageway sections.
In the case where the main inlet and outlet locations, and any auxiliary such locations, are openings as aforesaid, these fixed abutment surfaces may be edges of the openings whereby the clamp member abutment surfaces are movable transversely across the openings to trap the elongate member between the opening edges and the clamp member abutment surfaces.
Conveniently the clamp member may comprise a bar which has one end region slidably located within an opening in the side wall of the housing. An adjustment device may be provided for affecting sliding movement of the bar between clamp and release positions. This adjustment device may comprise a bolt held captive in the side wall of the housing and which engages a threaded bore at the end of the bar opposite to the aforesaid end region whereby movement of the bar is effected by rotation of the bolt.
The housing may be provided with an adjustable link structure for attachment of the housing to a switch member. This link structure may comprise a rod projecting from the housing which is joined to a hook via a screw mechanism of adjustable length.